Sanches Francisco (c.1551–1623), Portugueseborn philosopher and physician. Raised in southern France, he took his medical degree at the University of Montpellier. After a decade of medical practice he was professor of philosophy at the University of Toulouse and later professor of medicine there.
His most important work, Quod nihil scitur (That Nothing Is Known, 1581), is a classic of skeptical argumentation. Written at the same time that his cousin, Montaigne, wrote the ‘Apology for Raimund Sebond,’ it devastatingly criticized the Aristotelian theory of knowledge. He began by declaring that he did not even know if he knew nothing. Then he examined the Aristotelian view that science consists of certain knowledge gained by demonstrations from true definitions. First of all, we do not possess such definitions, since all our definitions are just arbitrary names of things. The Aristotelian theory of demonstration is useless, since in syllogistic reasoning the conclusion has to be part of the evidence for the premises. E.g., how can one know that all men are mortal unless one knows that Socrates is mortal? Also, anything can be proven by syllogistic reasoning if one chooses the right premises. This does not produce real knowledge. Further we cannot know anything through its causes, since one would have to know the causes of the causes, and the causes of these, ad infinitum. Sanches also attacked the Platonic theory of knowledge, since mathematical knowledge is about ideal rather than real objects. Mathematics is only hypothetical. Its relevance to experience is not known. True science would consist of perfect knowledge of a thing. Each particular would be understood in and by itself. Such knowledge can be attained only by God. We cannot study objects one by one, since they are all interrelated and interconnected. Our faculties are also not reliable enough. Hence genuine knowledge cannot be attained by humans. What we can do, using ‘scientific method’ (a term first used by Sanches), is gather careful empirical information and make cautious judgments about it. His views were well known in the seventeenth century, and may have inspired the ‘mitigated skepticism’ of Gassendi and others. See also SKEPTICIS. R.H.P.